[El Gato]

IIRC each MRE is somewhere between 5000 & 7500 calories.

According to the Army's Natick Labs, via Defense Supply Center, Philadelphia they contain 1,250 Calories (actually kilocalories, but dietary folks use Calories when they mean the physicist's (and engineer's) kilocalorie)

[Cvengr]

Here is an interesting compendium.

http://www.usariem.army.mil/nutri/milrat.htm

Instead of 1250 cal/MRE it suggests each MRE is 4044 cal/MRE IV.

I always thought the Cold Weather LRP was the high calorie meal, but am mistaken. It is shown at closer to 1553 cal/meal, but lighter weight.

See http://www.usariem.army.mil/nutri/appenda.htm